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We conducted a matched retrospective cohort study of two cohorts to estimate inactivated vaccine effectiveness (VE) and its comparative effectiveness of booster dose among older people in Shanghai. Cohort 1 consisted of a vaccinated group (≥1 dose) and an unvaccinated group (3,317,475 pairs), and cohort 2 consisted of a booster vaccinated group and a fully vaccinated group (2,084,721 pairs). The Kaplan–Meier method and Cox regression models were used to estimate risk and hazard ratios (HRs) study outcomes. For cohort 1, the overall estimated VEs of ≥1 dose of inactivated vaccine against SARS-CoV-2 infection, severe/critical Covid-19, and Covid-19 related death were 24.7% (95%CI 23.7%−25.7%), 86.6% (83.1%−89.4%), and 93.2% (88.0%−96.1%), respectively. Subset analysis showed that the booster vaccination provided greatest protection. For cohort 2, compared with full vaccination, relative VEs of booster dose against corresponding outcome were 16.3% (14.4%−17.9%), 60.5% (37.8%−74.9%), and 81.7% (17.5%−95.9%). Here we show, although under the scenario of persistent dynamic zero-Covid policy and non-pharmaceutical interventions, promoting high uptake of the full vaccination series and booster dose among older adults is critically important. Timely vaccination with the booster dose provided effective protection against Covid-19 outcomes.

Background Limited data are available on the effectiveness of inactivated and Ad5-nCoV COVID-19 vaccines in real-world use—especially against Omicron variants in SARS-CoV-2 infection-naïve population. Methods A matched case-control study was conducted among people aged ≥ 3 years between 2 December 2021 and 13 May 2022. Cases were SARS-CoV-2-infected individuals, individuals with severe/critical COVID-19, or COVID-19-related deaths. Controls were selected from consecutively test-negative individuals at the same time as cases were diagnosed and were exact-matched on year-of-age, gender, birthplace, illness onset date, and residential district in ratios of 1:1 with infected individuals and 4:1 with severe/critical COVID-19 and COVID-19-related death. Additionally, two subsets were constructed to analyze separate vaccine effectiveness (VE) of inactivated vaccines (subset 1) and Ad5-vectored vaccine (subset 2) against each of the three outcomes. Results Our study included 612,597 documented SARS-CoV-2 infections, among which 1485 progressed to severe or critical illness and 568 died. Administering COVID-19 vaccines provided limited protection against SARS-CoV-2 infection across all age groups (overall VE: 16.0%, 95% CI: 15.1–17.0%) but high protection against severe/critical illness (88.6%, 85.8–90.8%) and COVID-19-related death (91.6%, 86.8–94.6%). In subset 1, inactivated vaccine showed 16.3% (15.4–17.2%) effective against infection, 88.6% (85.8–90.9%) effective against severe/critical COVIID-19, and 91.7% (86.9–94.7%) against COVID-19 death. Booster vaccination with inactivated vaccines enhanced protection against severe COVID-19 (92.7%, 90.1–94.6%) and COVID-19 death (95.9%, 91.4–98.1%). Inactivated VE against infection began to wane 12 weeks after the last dose, but two and three doses sustained high protection levels (> 80%) against severe/critical illness and death, while subset 2 showed Ad5-vectored vaccine was 13.2% (10.9–15.5%) effective against infection and 77.9% (15.6–94.2%) effective against severe/critical COVIID-19. Conclusions Our real-world study found high and durable two- and three-dose inactivated VE against Omicron-associated severe/critical illness and death across all age groups, but lower effectiveness against Omicron infection, which reinforces the critical importance of full-series vaccination and timely booster dose administration for all eligible individuals.

Background Genital tract infections with ureaplasma urealyticum (UU) and chlamydia trachomatis (CT) are the most frequent sexually transmitted infections (STIs). The aim of this study is to understand the prevalence of UU and CT among general internal married migrants and to explore some possible influencing factors, so as to provide some evidences for STIs prevention in China. Methods A cross-sectional study was conducted in three cities of China from March 2016 to February 2017. A total of 3180 internal-married migrants were included. The structured questionnaire survey, gynecological or andrology examination and laboratory detection were conducted by the trained research fellow s. The prevalence of UU and CT was laboratory-confirmed in this study. Results The prevalence of laboratory-confirmed UU and CT were 45.41%, 5.75%, respectively. The co-infection rate was 4.09%. The rates of UU and CT of Shanghai participants (54.01%, 7.35%) were the highest, and the lowest were that of Yinchuan (37.74%, 4.52%). In Urumqi, the prevalence of UU and CT were 44.77%, 5.42%, respectively, but it has the highest co-infection rate. The multiple stepwise logistic regressions found that the prevalence of UU among three cities were different, and the male’s UU infection was lower than that of women (OR=0.71, 95%CI:0.61-0.83), and the 20-34 age group participants had lower UU and CT risk, compared with that of 45-49 age group. Moreover, the white-collar workers had lower risk of UU infection (OR=0.64, 95%CI: 0.49-0.83), compared with laborer, and using condom could reduce the UU infection (OR=0.74, 95%CI: 0.63-0.87). Compared with urban migrants, the rural participants had higher risk of CT infection (OR=1.68, 95%CI: 1.12-2.52), and sex behavior during menstruation could increase the prevalence of CT (OR=1.49, 95%CI: 1.05-2.11). Conclusion The prevalence of UU and CT were high and the co-infection was also serious among general internal married migrants. More health promotion measures about UU and CT should be taken to help general migrants of China, especially women and those with lower social-economic status (laborers from rural area), risky sexual behaviors such as having sex during menstruation should be warned of and condom-use should be promoted.